The present invention is directed to a display device wherein the viewing side of the display device has a watermark area and a non-watermark area and the display cells in the watermark area are modulated to be distinguishable from the display cells in the non-watermark area. The display device comprising the watermark feature is useful for protecting against counterfeiting or decoration purposes.
U.S. Pat. Nos. 6,930,818 and 6,795,138 disclose image display devices based on the microcup technology. The patents describe the manufacture of microcups as display cells. The microcups are then filled with a display fluid. The top openings of the microcups may have the same size and shape and such microcups spread across the entire display surface.